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Cold agglutination test

Coldagglutininn (Ca), discovered by Peterson in 1943 from the serum of patients with primary atypical pneumonia, is an anti-erythrocyte I antigen IgM antibody. At 56 ° C for 30 min, it remains active. Under the low temperature condition of 0-5 ° C, any blood type of A, B and O can agglutinate with its own red blood cells and O-type and homologous blood cells, which is a non-specific combination. For the diagnosis of pneumonia caused by Mycoplasma pneumoniae.

Above normal: Above normal, it is seen in Mycoplasma pneumoniae infection.

negative: Negative is normal.

Positive: Positive can be found in Mycoplasma pneumoniae infection, other such as infectious mononucleosis, severe anemia, malaria, myeloma, mumps, spirochete, ascariasis, trypanosomiasis, staphylococcal sepsis, cirrhosis, etc. can also be positive .

Tips: After 8 pm on the day before the medical examination, you should start fasting for 12 hours, so as not to affect the test results. Normal value

Serum titer < 1:32.

Clinical significance

95% of normal people have Ca in their blood, but their titer is more than 1:16, about 1% can reach 1:32 or more; patients with Mycoplasma pneumoniae infection have more Ca, and the increase is up. 34% to 68%, up to 1:32 to 1:64 or higher after the second week of infection, peaked at week 4. It is worth noting that 40% to 50% of the initial patients, the agglutination titer is quite low, therefore, every 1 to 2 weeks after the onset of the disease, the titer is 4 times higher, it has a certain diagnostic significance. Others such as infectious mononucleosis, severe anemia, malaria, myeloma, mumps, spirochete, ascariasis, trypanosomiasis, staphylococcal sepsis, cirrhosis, etc. may also be positive. About one-fourth of patients with autoimmune hemolytic anemia are caused by IgM-type cold antibodies (also known as clotting factors), some of which may be secondary to mycoplasmal pneumonia, characterized by chronic mild anemia, usually worsening in winter. The cold and exposed skin and facial skin appear painful purpura and hand and foot arterial spasm, the agglutination test titer is often very high, up to hundreds of thousands or even higher, so the results of this test must be combined with the patient's clinical symptoms for comprehensive analysis .

1, do not eat too greasy, high-protein food the day before the blood, to avoid heavy drinking. The alcohol content in the blood directly affects the test results.

2. After 8 pm on the day before the medical examination, you should start fasting for 12 hours to avoid affecting the test results.

3, should relax when taking blood, to avoid the contraction of blood vessels caused by fear, increase the difficulty of blood collection.

After inspection:

1. After blood is drawn, local compression is required at the pinhole for 3-5 minutes to stop bleeding. Note: Do not rub, so as not to cause subcutaneous hematoma.

2, the pressing time should be sufficient. There is a difference in clotting time for each person, and some people need a little longer to clotting. Therefore, when the surface of the skin appears to be bleeding, the compression is stopped immediately, and the blood may be infiltrated into the skin due to incomplete hemostasis. Therefore, the compression time is longer to completely stop bleeding. If there is a tendency to bleed, the compression time should be extended.

3, after the blood draw symptoms of fainting such as: dizziness, vertigo, fatigue, etc. should immediately lie down, drink a small amount of syrup, and then undergo a physical examination after the symptoms are relieved.

4. If there is localized congestion, use a warm towel after 24 hours to promote absorption.

Inspection process

Inspection process:

Blood is drawn, and blood is taken for examination. Generally, venous blood is taken, and blood is drawn by a doctor or a nurse. The amount of blood drawn is determined according to the difference of the test content and the number of items. The blood volume is usually 2-20 ml, and the maximum is not more than 50 ml. The cold agglutination test of the antibody was performed by a doctor after the blood was drawn.

Not suitable for the crowd

Those who do not have an indication for examination should not do this check.